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Author Topic: Combining different length exposures...  (Read 3326 times)

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Offline janmclare

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Combining different length exposures...
« on: 23:36:14, 04 March, 2006 »

When stacking exposures of different lenghts on an object like m42 what method should be used to combine the frames so the core does not get burned out.
At the momment i'm masking it out from the longer exposures in photoshop. Just wondering if its possible to do it  automatically whilst stacking in Maxim.

Jan
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Offline rob uk

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Re: Stacking question...
« Reply #1 on: 00:26:24, 05 March, 2006 »
isent really anything you can do stacking wise but once you have the stacked pic you can take it into PS for a play http://www.astropix.com/HTML/J_DIGIT/COMP2.HTM

Offline janmclare

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Re: Stacking question...
« Reply #2 on: 01:12:56, 05 March, 2006 »


Thats seems easier to what i'm doing now ... will give it a try next time...:)

Jan
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Offline dciobota

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Re: Stacking question...
« Reply #3 on: 17:09:15, 06 March, 2006 »
  Great link Rob, thanks!  I saw this one before, but somehow lost the link.  Wow, I just came back from out of town and find all this wealth of info... cool!  :D

Daniel
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Offline synner

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Re: Combining different length exposures...
« Reply #4 on: 17:16:44, 06 March, 2006 »
I've amended the title of this thread and made it sticky, 'cause that little nugget from Mr Lodriguss is a gem 8-)
Nick
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Offline dciobota

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Re: Combining different length exposures...
« Reply #5 on: 17:26:32, 06 March, 2006 »
  :mrgreen:

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Offline tommi

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Re: Combining different length exposures...
« Reply #6 on: 22:13:05, 12 March, 2006 »
Hi Jan

I have found it easier myself to use two sets of  long and short exposures acquired and combined in Maxim. Cut, feather and paste the shorter exposed area onto a duplicate long exposure image in Photoshop, it can be done in Maxim with a lot of messing around but why bother when it is that easy in PS.

Cheers Tommi


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Offline janmclare

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Re: Combining different length exposures...
« Reply #7 on: 00:20:08, 13 March, 2006 »

Cool thanks for that tommi...:)  seems like there are lots of way to achieve the same result. That looks great btw, can't tell at all...


Jan
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Offline mcrossley

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Re: Combining different length exposures...
« Reply #8 on: 20:04:18, 16 April, 2006 »
And if you do a bit of 'rithmatic and have CS2 you can combine them into a HDR (High Dynamic Range = 32bit) image.  The images have to be pre-aligned though, but it avoids any masking etc. just adjust the curves on the combined image, then save it as a 16bit image.
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Re: Combining different length exposures...
« Reply #9 on: 19:27:14, 08 December, 2006 »
Jan

there is a semi automatic method method you can use in PS but it takes a bit of getting used to. The basic idea is to take two exposures and use the darker of the two to fill in the bright core. Instead of using a selection which is a bit rough and ready you need to use a layer mask, using the darker frame as the mask but blurring it so that it has no hard edges anywhere. If you use a standard selection and feather it you can generally only feather the edges, not the brightness variations within the frame.

Once you have the blurred layer mask in place you can adjust the contrast and brightness of it to make it darken the core in a very progressive way. I have a recently posted image of M42 in the deep sky section that uses this technique.

Dennnis Isaacs

 

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